With the recent widespread of such a photographic apparatus as a camera, photo-taking opportunities have also increased with the use of a silver halide photographic light-sensitive material.
According thereto, there have been increasing demands for making sensitivity and image-quality higher.
One of the dominant factors to the high sensitivity and high image-quality of a silver halide photographic light-sensitive material is a silver halide grain. The research and development of a silver halide grain have also been progressed so far in the field of the art, with the purpose of making the sensitivity and image-quality thereof to be higher.
However, there has been a limit to satisfy both of a high sensitivity and high image-quality, because the sensitivity thereof is liable to be lowered when a silver halide grain is made smaller in grain-diameter so as to improve the image-quality, as has usually been tried.
For trying to make a sensitivity and an image-quality more higher, there have studied the techniques for improving the ratio of a sensitivity/a grain-diameter per silver halide grain. Japanese Patent Publication Open to Public Inspection (hereinafter referred to as JP OPI Publication) Nos. 58-111935/1983, 58-111936/1983, 58-111937/1983, 58-113927/1983 and 59-99433/1984 disclose each such a technique as mentioned above in which the so-called tabular-shaped silver halide grains are used.
As the tabular-shaped silver halide grain is compared with the so-called normally crystallized silver halide grains such as those of an octahedron, an decahedron or a hexahedron, the former has such an advantage that the sensitivity thereof can be made more higher, because, when the volume of the silver halide grain of the former is the same as in the latter, the surface area of the former can be larger, so that many sensitizing dyes can be absorbed on the surface of the silver halide grain.
Also, JP OPI Publication No. 63-92942/1988 describes a technique in which a core having a high silver iodide content is arranged to the inside of a tabular-shaped silver halide grain; JP OPI Publication No. 63-151618/1988 describes a technique in which a hexagonal, tabular-shaped silver halide grain is used; and JP OPI Publication No. 63-163451/1988 describes a technique in which a tabular-shaped silver halide grain having not less than 5 in a ratio of the grain thickness thereof/the longest distance between the twined crystals thereof. These patent publications also indicate each the effects on a sensitivity and a graininess.
Further, JP OPI Publication No. 63-106746/1988 describes a technique making use of a tabular-shaped silver halide grain having substantially a layer-structure parallel to two major faces opposed to each other; and JP OPI Publication No. 1-279237/1989 describes a technique making use of a tabular-shaped silver halide grain having a layer-structure partitioned substantially by a plane parallel to two major faces opposed to each other, and having an average silver iodide content of the outermost layer that is at least not less than 1 mol % higher than the average silver iodide content of the whole silver halide grain.
Still further, JP OPI Publication No. 1-183644/1989 discloses a technique making use of a tabular-shaped silver halide grain comprising silver halide containing silver iodide having a completely uniform silver iodide distribution.
Besides the above, there is also a known technique in which a carrier can be controlled in a metal doping treatment.
The above-mentioned metal-doping treatment is a technique in which photographic characteristics can be improved by containing mainly a polyvalent metal compound in a silver halide grain.
JP OPI Publication Nos. 62-7042/1987 and 1-105940/1989 disclose each a technique for doping an Ir ion, and JP OPI Publication No. 1-121844/1989 discloses a technique for doping an Fe ion.
JP OPI Publication Nos. 3-196135/1991 and 3-189641/1991 disclose each a silver halide photographic emulsion prepared in the presence of an oxidizer for silver, and the effects to a sensitivity and fogginess each produced when making use of a silver halide photographic light-sensitive material in which the emulsion is used.
Further, for example, JP OPI Publication No. 63-220238/1988 discloses a technique for making use of a silver halide emulsion containing a tabular-shaped silver halide grain having a specified dislocation line number; JP OPI Publication No. 3-175440/1991 discloses a technique for making use of a silver halide emulsion containing tabular-shaped silver halide grains having the dislocation points concentrated in the neighborhood of the apices of the grains; JP Examined Publication No. 3-18695/1991 discloses a technique for making use of silver halide grains having a clear core/shell structure; and JP Examined Publication No. 3-1245/1991 describes a technique concerning a core/shell structured silver halide grain. The above-mentioned techniques have been studied respectively as a high sensitization technique.
However, these conventional techniques have a limit to satisfy both of a high sensitivity and a high image-quality at the same time, and these techniques are not satisfactory to provide a sensitivity and an image-quality each required of the recent light-sensitive materials. Therefore, a development of a superior technique has been demanded.